Preparation of moisture resistant thread



Patented Oct. 15, 1935 PREPARATION OF MOISTURE RESISTANT THREAD Cyril J. Stand and Russel H. Van Dyke, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New York I No Drawing. Application July 22, 1932, Serial No. 624,149

17 Claims.

The present invention relates to a process of preparing moisture resistant thread by treating it with an acetylation bath containing a non-esterifiable plasticizer.

a It is known to treat cotton yarn with a mixture of acetic anhydrid, acetic acid and a catalyst such as zinc chloride to produce dye resistant effect threads for use in fabrics to produce various effects due to the fact that those threads will resist dyes which other threads of the fabric are susceptible to. Maximum moisture resistance in those effect threads was of little importance as the main concern was to acetylate the threads only to impart dye-resistant properties thereto.

The electrical industry has been in need of thread, for insulation purposes, characterized by high electrical insulating ability, 10w moisture absorption, high tensile strength and low inflammability. Obviously the last characteristic desired would exclude thread of the nitrocellulose type. We therefore directed our attention to the use of a thread of cellulose which had been acetylated. It is known that cellulose triacetate has a much lower moisture absorption value than that of una'cetylated cellulose and that its value for electrical insulation is much higher. However we found that when we attempted to acetylate thread to the triacetate or nearly so, the resulting thread was so weak as to lack utility for insulation purposes. On the other hand when the thread was only partially acetylated so that the tensile strength would not be unduly decreased, the moisture absorption was not lowered as much as might be desired. One object of our invention is to provide a process of preparing threads suitable for electrical insulation purposes which threads are satisfactory as to insulating value, moisture resistance, tensile strength and inflammability. Another object of our invention is to provide a process. of preparing threads, for electrical insulation purposes which is'simple in that it involves merely the step of treating the thread with an acetylating bath. Other objects will hereinafter appear.

We have found that a cotton thread may be subjected toan acetylating treatment and still exhibit both high tensile strength and low moisture absorption. We have found that a thread eminently suited for electrical insulation pur- (ops-20) poses may be prepared by treating a cotton thread with an acetylating bath containing a non-esterifiable plasticizer. We have found that if a small amount of some one of the non-esterifiable plasticizers frequently employed to plasti- 5 cize cellulose acetate is added to the acetylation mixture used in the acetylation of thread, that the resulting thread has a moisture absorption which is 60-70% lower than that of the original thread and 25-30% lower than that of a thread 10 acetylated in the absence of a plasticizer under conditions by which it will not lose its tensile strength.

The following examples illustrate the application of our invention in the preparation of par- 15 tially acetylated thread and are not for the purpose of limiting the scope of our invention.

' Ezvample I sulfuric and phosphoric acids such as disclosed in 30 Gray & Staud U. S. Patent No. 1,683,347) and 5 lbs. of triphenyl phosphate. The temperature of the mass was raised from 20 to 40 C. over a period of 2 hours and it was then maintained at 40 for 4 hours. The thread was separated from 35 the reaction bath and washed to neutrality using only water. The thread obtained was analyzed for acetyl and plasticizer content and for tensile strength and moisture absorption with the following results: 40

Acetyl content 27.7 Triphenyl phosphate 10.18% Tensile strength 330 gms. Moisture absorption 2.34%

at 55% relative humidity.

When some of the same kind of unbleached thread was acetylated in the same manner as in the above example except that no plasticizer was employed in the bath, the thread obtained tested as follows:

Acetyl content 27.7%

Tensile strength 340 gms.

Moisture absorption 4.05% at 55% relative humidity.

The original unacetylated thread which was employed in the example was tested in the same manner with the following results:

Acetyl content 0% Tensile strength 300 gms.

Moisture absorption 5.89% at 59% relative humidity.

Thus it may be seen that in the three samples tested that one prepared by the process of our invention only exhibited that happy combination of high moisture resistance coupled with high tensile strength.

Example II An unbleached cotton thread such as employed in the preceding example was acetylated in the same manner as in that example except that tricresyl phosphate was substituted in like amount for triphenyl phosphate. The resulting product tested as follows:

Acetyl content 29.1% Tricresyl phosphate 8.6% Tensile strength 380 gms. Moisture absorption 2.5%

at 55% relative humidity.

Example III Example I was repeated except that diethyl phthalate was substituted in like amount for triphenyl phosphate. The thread prepared by this example tested as follows:

Acetyl content 29.6 Diethyl phthala'te 4.50% Tensile strength 345 grams Moisture absorption 2.58%

at 55% relative humidity.

Example IV Example I was repeated except that o-cresyl ptoluene sulfonate was substituted in like amount for the triphenyl phosphate. The following data on the resulting product were obtained:

Acetyl content 30.8% O-cresyl p-toluene sulfonate 9.13%. Tensile strength 310 grams Moisture absorption 2.89%

at 55% relative humidity.

The term fibrous esterifying bath is to be understood as referring to an esteriflcation bath which is a non-solvent of the cellulose ester which is formed therein.

Example V About 10 lbs. of unbleached cotton thread was pretreated for 16 hours at 20-25 C. with 70 lbs. of glacial acetic acid. The mass was then Dressed down to lbs. and a mixture of 26 lbs. of acetic anhydrid (99%) about a lb. of a catalyst such as employed in Example I, 42 lbs. of henzene and 5 lbs. of diphenyl phthalate was added thereto. The temperature of the mass was raised from 20 to 40 C. over a. period of 2 hours and was maintained at 40 for about 4 hours. The thread was removed and washed to neutrality with water. The following data were obtained on this sample:

Acetyl content 26.9% Diphenyl phthalate 9.53% 5 Tensile strength 360 grams Moisture absorption 2.14%

at 67% relative humidity.

The examples given are obviously fibrous esteriiication processes so that other suitable nonsolvents of cellulose acetate such as ether, benzine, toluene, etc. may be employed as diluents in the thread esterification processes. Also in stead of the phosphoric-sulfuric acid catalyst employed, other wellknown esterification catalysts may be employed in the carrying out of our invention. Also other fatty acid compounds than acetic may be employed in the process of preparing moisture-resistant thread according to our invention. For example the acetic anhydrid may be replaced wholly or in part by propionio or butyric anhydrides or a mixture of those anhydrides.

Various other modifications of our process such 25 as are made possible by variations in materials, time, temperature, proportions or other conditions of a technical nature are obvious to those skilled in the art and also come within the scope of our invention. For example the cellulose to so be treated instead of being in thread form may be in the form of sheets, strips or some other desired physical form.

We claim as our invention:

1. The process of preparing an acylated cellu- 2. The process of preparing an acetylated 081- 40 lulose suitable for electrical insulation which comprises treating the cellulose with an esterifying bath comprising an acetic acid anhydrid in the presence of a non-esterifiable plasticizer.

3. The process of preparing an acetylated cellulose thread suitable for electrical insulation which comprises treating the thread with an esterifying bath comprising an acetic acid anhydrid in the presence of a non-esterifiable plasticizer.

4. The process of preparing an acylated cellulose suitable for electrical insulation which comprises treating the cellulose with a fibrous esterifying bath comprising a lower fatty acid anhydrid in the presence of a non-esterifiable plasticizer.

5. The process of preparing an acylated ce1- lulose thread suitable for electrical insulation which comprises treating the thread with a fibrous esterifying bath comprising a lower fatty acid anhydrid in the presence of a non-esterifiable plasticizer.

6. The process of preparing an acetylated cellulose thread suitable for electrical insulation which comprises treating the thread with a fibrous 05 esterifying bath comprising acetic anhydrid in the presence of a non-esterifiable plasticizer.

7 The process of preparing an acylated cellulose thread suitable for electrical insulation which comprises treating the thread with an esterl. ying bath comprising a lower fatty acid anhydrid in the presence of a triaryl phosphate.

8. The process of preparing an acetylated cellulose suitable for electrical insulation which comprises treating the cellulose with an esterifying 76 bath comprising acetic anhydrid in the presence of a triaryl phosphate.

9. The process of preparing an acylated cellulose thread suitable for electrical insulation which comprises treating the thread with an esterifying bath comprising a lower fatty acid anhydrid in the presence of triphenyl phosphate.

10. The process of preparing an acetylated cellulose suitable for electrical insulation which comprises treating the cellulose with an esterifying bath comprising acetic anhydrid in the presence 7 of a triphenyl phosphate.

11. The process of preparing an acylated cellulose thread suitable for electrical insulation which comprises treating the thread with a fibrous esterifying bath comprising a lower fatty acid anhydrid, and a diluent in the presence of a nonesterifiable plasticizer.

12. The process of preparing an acetylated cellulose thread suitable for electrical insulation which comprises treating the thread with a fibrous esterifying bath comprising acetic anhydrid, and a diluent in the presence of a non-esterifiable plasticizer.

13. The process of preparing an acetylated cellulose thread suitable for electrical insulation which comprises treating the thread with a fibrous esterifying bath comprising acetic anhydrid, and a diluent in the presence of a non-esterifiable triaryl phosphate.

14. The process of preparing an acylated cellulose thread suitablefor electrical insulation which comprises treating the thread with a fibrous esterifying bath, comprising a lower fatty acid anhydrid and as a diluent, carbon tetrachloride, in the presence of a non-esterifiable plasticizer.

15. The process of preparing an acetylatedlcellulose thread suitable for electrical insulation which comprises treating the thread with a fibrous esterifying bath comprising acetic anhydrid and as a diluent, carbon tetrachloride, in the presence of a non-esterifiable plasticizer.

16. The process of preparing an acetylated cellulose thread suitable for electrical insulation which comprises treating the thread with a fibrous esterifying bath comprising acetic anhydrid and as a diluent, carbon tetrachloride, in the presence of a triaryl phosphate.

17. The partially acetylated cellulose resulting from the fibrous acetylation of cellulose in the presence of a non-esterifiable plasticizer.

CYRIL J. STAUD. RUSSEL H. VAN DYKE.

CER'i'iFiCRTE OF CGRRECTION,

Patent No. 2,017,172. October 15, 1935.

KJYRKL J. STAUD, ET AL.

It is hereby certified thai error appears in the printed specification of the aimve numbered paient requiring correctien as follows: Page i, seaond mlumn, line 42, far "27.7%" read 34.2%; and that the: said Letters Patent should be read with this correc ion therein that the same may reniorm to the record of the case in the Patent Office.

Signed and sealed this 10th day 0i Desember, A. D. 1935.

Leslie Frazer (Seal) Acting Commissioner oi Patents.

IERTiFiG iTE OF C(JRRECTION.

Patent No. 2,017,171. October 15, 1935.

CYREL J. STAUD, ET AL.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page I, second column, line 42, for "27.7%" read 34.2%; and that the said Letters Patent should be read with this correc ion therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 10th day of December, A. D. 1935.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

